Coffee infusion apparatus



J. S. COMSTOCK COFFEE INFUSION APPARATUS Filed Dec. 31, 1954 2 Sheets-Sheet l 'III Dec. 13, 1938.

DeC- 13, 1938 .1 s. coMsTocK COFFEE INFUSION APPARATUS Filed Dec. 3l, l934 2 Sheets-Sheet 2 172 D enf/or fofz. fef/zhy fans/aci,

Patented Dec. 1,3, 1938 UNITED lSTATES PATENr o1-FICE 4 claims.

This invention relates to means for making coilee infusions, it being the general -object of the invention to provide an improved coffee infusion apparatus ycapable of making a coilee beverage 5 of improved character. v

' A large number of methods for making a coffee beverage are known, differing in the amount ofQ heat used, the time of extraction, the pressure maintained in the infusion chamber, in whether or not the coiee is subjected to boiling, etc.

Present methods of making coilee may be divided into filtration-bed methods, in which the ground coiee forms a mass through which the water seeps, and methods in which the coiee particles float freely in a relatively large quantity of hot Water. The old-fashioned method consisting in boiling the coee ina coffee pot is an example of the latter method, while so-called drip and percolator coffee making methods belong in the rst mentioned category. In the instance of coiee grounds floating freely in water, the coffee grounds, until thoroughly wetted o r stirred, will iioat as a cake or crust at the surface, and when wetted sink and form a bed at the bottom of the container.

Attempts have been made to extract the coifee beverage by a general method which involves use of a tightly closed chamber within which the ground coffee is placed, the chamber being pro- '30 vided with an inlet channel for introduction of hot water under pressure, and an outlet channel, controlled by a lter, through which the coiee beverage is nally discharged. Such a." method and apparatus has certain attractive theoretical advantages, in that it lends itself to many convenient and labor-saving forms of coffee making equipment, and also in that it prevents escape of the aromatic essences of the coffee bean,

so desirable to the coffee beverage. In practice, 40'however, certain diiiiculties have been encountered, and the process in question has not heretofore met with any measure of success. For instance, without the.provision of some preventive means, thepressure conditions within the chamber cause the ground coffee to pack tightly in a bed, This effect causes flow of the coffee through the chamber to be restricted to such an extent as to nulliiy entirely the advantages of the method. Further, the tight packing of the grounds causes certain portions ofthe coffee to be shielded from the action of the water, while otherportions, because of the larger amount of water with which they come into contact, are over-extracted, A bitter and characterless bevi erage results. And in addition to this, for some -coiee infusion is'"formed in a closed chamber.

'water is introduced to the chamber, and at the (Cl. I53-3) the preceding paragraph, but which overcomes all of the previously encountered disadvantages and disabilities of said method. Itis a further object of the invention to provide a coffee making apparatus which is highly conducive to bringing about an extraction and preservation of the desirable and more volatile aromatic oils of the coffee, while permitting the dissolving of but a 20 minimum quantity of certain coffee elements which have a, deleterious eiect upon the beverage. or are unwholesome in their effect upon the human system, and also to provide an apparatus in which the coffeeinfusion undergoes no chemical changes which aiect adversely the flne and delicate coffee avorwhich can alone be obtained fm the untransformed aromatic and relatively more volatile elements of the ground coiee bean. In accordance with my present invention, the

Preferably, the chamber containing a suitable measure of dryground coffee, after being closed, is subjected for a short period of time to preliminary heating, in the absence of moisture. This dry preheating has the eiect of releasingceiftain aromatic vapors from the coffee,l which are pre,- served within the chamber to be absorbed by the later introduced water, and also apparently prei pares for instant release the more volatile aro- 40 matic oils, so that extraction and assimilation of such elements by the hot water introduced later will be extremely rapid. However, this step, while definitely enhancing the iavor and character of the nal-beverage, may be eliminated, if desired, without destroying the beneilcial results obtained in the remainder'of the process.

.After preheating, or ifpreheating is not used, after closing of the extraction chamber, hotsame time some suitable agency is employed to v.maintain the liquid within the chamberin such al`A` state of agitation that the coifee grounds are maintained in free suspension in the liquid, being repeatedly submerged below the surface, and at f the same time being prevented from settling on Vthe bottom of the chamber. The introduced tures which with similar apparatus, have been found to cause turning of color in the coffee, or spoiling, if agitation were lacking. Agltation also assures that each grain of coiee will be exposed evenly and completely through the water bath, assuring as complete extraction as is desirable in a relatively short period of time. Because Vof the shortened time of extraction the baser, non-aromatic, woody elements, which are water soluble and come oil in proportion to the duration of the extraction period, are obtained to but relatively small extent. Because hotter water can be and is used, extraction of the volatile parts of the ground coffee is speeded, and the extraction of the volatile elements and desirable oils of the coiiee is highly promoted, while extraction of the baser, non-volatile elements is not correspondingly increased by the greater heat sucand more desirable coffee elements, accompanied -by reduction in extraction of the undesirable substances of the coee bean.

It vigorous agitation is not maintained under conditions mentioned, spoilage of the coee in evitably results. The eiect of which I speak is A not simphr failure to obtain the best coee, but

is a positive spoiling, probably due to Ysome chemical change within the coilee, the coil'ee rapidly changing color and taking on a bitter taste. The

. facts of' which I speak have been ascertained by test and experiment, and although I am not certain of the exact nature of the reactions which,

tively concentrated solution, certain reagents,

probably acid in nature, dissolved from the woody fiber of the bean, and a destructive reaction of some nature is set up between these vapors and the reagents which come from the'grolmds. If,

on the other hand, the bed of coeeY is constantlyabrokenv up, or prevented from forming, the concentration of these reacting vapors and acids is much decreased, and the destructive transformation is eii'ectively prevented.

It is a characteristic of a present preferredJ form of the invention that the hot water is introduced to a vapor tight coiee extraction or infusion chamber having a hot water inlet and a coiee infusion outlet, with a diierential of pressure being'maintainedbetween said inlet and outlet such that the hot water is introduced to the chamber with-suicient velocity to establish the vigorous agitation required, and such that the coiee ows properly through the chamber. As stated previously, the water is introduced at a temperature which may closely approach 100 C., andthe set of conditions thus established brings about very rapid extraction of the desired volatile and aromatic oils of the coiee, the de' scribed vigorous agitation of the water in the coiee is suspended preventing spoilage (deleterious physical or chemical change) of the bever-- age, as well as aiding extraction by assuring maximum exposure of each grain of coiee to the hot water. 'Ihe hot water is left in contact with the coffee grounds only for a period suiilcient to extract the lighter or more desirable elements oi Yof exposure, to produce a beverage so mild that,

if lequally mild coffee were produced by any usual method, it would be called watery and characterless, yet colee of such mildness will be palatable and delicious, when made by this process. amount of the coffee bean can be used so small that, while with other methods the beverage would be watery and characterless, yet with this method, the beverage, while mild, will hav character and `will be palatable. Byusin equal amounts of coee in a conventional process and in this process, and gauging the time and heat so that the strength of beverages will be about equal, the result will be that the coie made by this process is far more aromatic, full bodied, soft, and distinctive in character. The proportion of aromatic oils will behigher, and the proportion of baser acrid elements lower than in .the coffee made by the usual method.

Moreover, from any denite quantity of ground coffee, more beverage of equal strength and equal quality can be extracted than by any other method of which I am aware. AThis is a definite commercial advantage if quality is to be sacriced to quantity.

Finally, while it is usually expected that coffee, made by ordinary processes, will have become undrinkable if allowed to cool, and later reheated, it is my consistent experience that coffee made by Y- this process can be allowed to cool and then reheated, and even cooled and reheated several Air times, after which the coiee will be still very Y nearly as good as when fresh. It may be cooled and kept for several, days without appreciable deterioration.

v'I'he process as thus outlined may be carried out I' with special Vapparatus provided by the present invention. This apparatus is preferably of the general type involving a closed coiee extraction chamber, a means for injecting hot water thereto under pressure, provision being made for agitation of the liquid during the hot water injection,

and an outlet-conduit, protected by a filter, leadamasar The various novel features of invention of my apparatus, as well as various objects, advantages and details of my invention not preliminarily mentioned, will be set forth in detail in the following detailed description, reference for this purpose being had to the accompanying drawings,V

in which:

Fig. 1 is a vertical medial section through a preferred form of apparatus in accordance with the invention;

Fig. 2 is a side elevation of the apparatus shown in Fig. 1, being a view lopking at the device shown in Fig. 1 from the left as seen in that figure;

Fig. 3 is a detail taken as indicated by arrows 3--3 in Fig. 1;

Fig. 4 is a detail of a spring clamp;

Fig; 5 is a detail section of the upper end of the lter;

Fig. 6 is a detail section of the lower portion of the lter and its seat in the lower end of. the extraction chamber;

Fig. 7 is an enlarged detail of an air vent andrestricting plug;

Fig. 8 is a diagrammatic view indicating a modied form of apparatus; and I l Fig. 9 is a diagrammatic view indicating another modied form of apparatus.

In Fig.1 numeral I0 designates generally the coffee infusion or extraction chamber, this chamber being generally in the form of a vertically extending cylindrical casting. The lower end of the chamber is closed by a concave bottom wall I I. The upper end of the casting is open, and is provided with an external annular flange I2. Extending the length of one side of the chamber and underneath bottom wall I I is an enlargement I3 formed with a coifee discharge conduit I5. This conduit I5 communicates with the interior of chamber I by way of an opening I6 in the chamber bottom, and leads to a coffee discharge passageway I1 formed in a spout I8 cast integrally with part I3. The spout I8 4is near the upper end of the extraction chamber casting, as shown.

'Ihe upper end of the extraction chamber is closed by a removable top or dome 20, provided with an annular ange 2| adapted to seat on the aforementioned ange I2. Flange 2I is recessed in the manner shown at 22 to receive a exible pressure-sealing washer 23', which is adapted to bear down on the upper face of ange I2 and to be pressed thereagainst to seal the extraction chamber in a pressure tight manner. This top or dome 20 is adapted to be clamped tightly down through the instrumentality of a bail 26 which is trunnioned on opposite sides of the chamber, as-

at 21, and a cam member 21 which is mounted for pivotal movement on bail 26 and has an arcuate cam surface 28 adapted to be engaged with a complementary seating surface 29 formed in the center of the dome top.- Cam member 21 has a finger piece 30 by means of which it may be manipulated, and it will beunderstood that when the device is moved to the position of Fig. 1, the cam element presses top member downwardly and causes a slight compression of sealing washer 23 to seal the chamber in a pressure tight manner. To remove top member 28, it is only necessary to move finger piece 38 to an upright position which removes the cam member from its engagement with the top and permits the bail to be swung to one side and top member 20 to be removed. y

In the form of my invention here shown, the coffee chamber as described rests on and extends through an annular opening in the upper wall of a water boiler 40. This boiler is simply a water chamber, of suitable capacity, and of any form desired, formed at, the top with an opening of a diameter sumcient to pass the lower end d2 of chamber I8. Said chamber is formed near its lower end with an external annular flange 83 adapted to rest on a pressure sealing washer-4d placed on the annular shoulder t which defines the boiler opening di.

Extending upwardly from one side of the boiler, and communicating with the boiler at a point 49 near the lower end thereof, is a vertically extending pipe or `conduit 56. The upper end of this conduit 5l) is preferably at substantially the level of the upper end of the extraction chamber ange i2, and is formed with an enlargement 5i having a conical seating surface 52 adapted to receive the conical shaped lower end 53 of a pipefitting member 5t formed integrally with extraction chamber top 28. A exible pressure sealing washer 55 is shown placed between seating surface 52 and the conical lower end 53 of member 5d, and serves to aord a pressure tight joint at that point. As clearly shown, tting 5d' is formed with a channel 51 which leads from the upper end of pipe 58 and opens within dome member 28 at a level somewhat above seating flange 2l.

Threaded into the discharge end of passageway 51, within dome 28,1s a water discharge nozzle Gil, and in the preferred specific form here illustrated this nozzle embodies a rounded nose 6I provided with a substantially flat discharge orifice 52 (see Fig. 3). This orifice is odset from the center of the rounded nose, as shown, and the nozzle is positioned with the orifice on the lower side and disposed in a horizontal position, so that a flat, downwardly and outwardly directed jet of water issues therefrom. This jet of water strikes the surface of liquid within the extraction chamber at approximately its center area, this surface being established at a level approximately at the mouth of the-dome, as will hereafter appear.

A clamp device is provided for tightly seating the conical end 53 of tting 5d within its seat 52. For this purpose, I provide a bail 66 which is trunnioned at 81 on opposite sides of pipe 58, and is adapted to engage a seat 58 formed on the upper side of fitting 5d, as clearly shown .in Fig. l. The length of the bail is-such as to force tting 54 downwardly somewhat, and to compress sealing washer 55, as the bail is forced upwardly on its seat 58, thus providing a pressure tight t, as well as a connection that will not be'apt to become disengaged with steam pressure within the conduit. It will be noted that in the position of Fig. 1, the bail rests in a slight depression formed in seating surface 58, so that there is no tendency for the bail to slip off its seat when'pressure is exerted within the pipe.

Thus, in this preferred construction, dome or top 20 and water inlet pipe-fitting 54 are formed as a unit, and are removable from the apparatus together by disengaging bails 26 and 66.

It will be evident that bail 86 acting throughv chamber top 20 serves to hold the chamber downwardly against its seat 45 at the upper end of the boiler, there being, however, considerable give in this hold-down means alone. A spring clamp device is additionally provided, preferably on the side of the coffee chamber which is opposite to pipe 50 and bail 66, and serves to complete the clamping of the extractionchamber down to the boiler. In the preferred form here shown, this clamp device embodies a link 16 pivoted at 11 on the side of the chamber, and a bail, or loop-like link member- 18, the upper end of which slides vertically on link 16, and the lower end of which is adapted to engage below a catch 19A mounted on the boiler. A compression spring 80 is placed around link 16 between the upper end of loop 18 and a pair of adjustment nuts 8| screwthreaded on the lower end of link 16. It will be evident that bail 66 considered alone tends to hold the coffee extraction chamber downwardly against its seat at the upper end of the boiler, but that without further provisions the extraction chamber could easily be lifted well above its seat on the sealing washer 44 and shoulder 45. The clamp. device 15 is designed to hold the. device tightly, but yieldingly, down against sealing washer 4|, it being necessary to compress clamp spring 80 somewhat before loop 18 can be passed over catch 19. With a development of a certain pressure within the boiler, however, the downward force exerted on the extraction chamber by clamp spring 80 is overcome, and the extraction chamber lifts slightly to permit escape of steam ln the crack so made. It will be obvious that the steam pressure at which the steam is so allowed to escape will depend upon the force necessary to overcome clamp spring 80. This force is adjustable by changing the position of nuts 8| on link 16, and the steam pressure at which discharge occurs may accordingly be adjusted by means of these adjustment nuts. It will thus be evident that the extraction chamber itself forms a steam blow-off valve, and that the pressure at which said valve opens is adjustable by screwing nuts 8| up or down on link 16. The purpose of these provisions will appear at a later point in the specification.

There is preferably provided in pipe 50 a shutofl' valve 10, provided with a suitable hand wheel 1|, as shown.

Preferably, a small bleeder hole 84 is provided in the top of the boiler, its purpose being to allow air in the boiler to escape during the warmingup process, thereby kavoiding premature build-up of pressure and flow of luke warm water from the boiler. In case valve 10 be left open from the beginning or eliminated, this bleeder hole or equivalent is essential.

A cleaning port 81 is formed just above the juncture of conduit I with discharge spout passage I1, and this port is normally closed by a plug member 88 provided with a seating flange 89. This plug may have an extension 90 pivoted to the spout at 9|, and the arrangement of parts may be such that its seating ange 89 is engaged on its upper face by a downwardly extending rim 92 formed on the flange portion of top member 20 when the top member is mounted on the extraction chamber. The cleaning plug thus is engaged by the extraction chamber top when said top is in place, so that the plug cannot comeopen during operation of the apparatus; when the ex traction chamber top has been removed, however, the plug may be swung back to enable insertion of a cleaning brush through port 81 and into channel I5.

Numeral 95 designates the filter. This filter, in its preferred form, embodies a vertically elongated wire frame work 96, of substantially the form of a cylinder, covered by a cloth filter bag 91. Wire frame 96 is mounted at the bottom on a mounting ring 90, the lower end of which is formed with a rounded annular flange 99 adapted to be received within conical seat |00 formed in bottom wall outlet opening I6. With this arrangement, a good seat is afforded for ring 98 within seat |00 even though the filter may not always be placed in an exactly vertical position when it is placed in the extraction chamber. Aiiixed to the upper end of the filter frame is a disk |02, having extending upwardly therefrom a spring hold-down member |04. This holddown spring has a bend at |04a, as shown, and has at its upper end a disengageable seat in the extraction chamber wall, whereby it presses downwardly in the upper end of the filter and holds the latterin place during operation of the apparatus. The nature of the engagement of the spring with the chamber wall as here shown will be described presently.

The cloth filter bag is drawn tightly around the lower end of the spring member, above disk |02, the upper end of the bag having a small hole |06 through which the spring member is inserted at the time the filter bag is placed on the filter frame. frame and extends downwardly over the upper portion of ring member 98, the lower end of the bag being held tightly in place by means of a drawstring |08 drawn tightly and fastened withinf-an annular groove |09 formed in the exterior surface of said ring, in the manner clearly shown.

Hold-down spring |04 has at its upper end an enlargement ||0 adapted to be engaged within the inner end of an air vent or passageway formed in the chamber wall near the upper end thereof. This passageway is substantially opposite discharge spout passageway |1, and communicates therewith and with passageway l5 in the manner shown. Passageway serves not only as a means for receiving and positioning the upper end of the filter hold-down spring, but also as an' air outlet from the extraction chamber. It is necessary that this air outlet be more or less definite in size, and also that it be of a relatively restricted nature. In particular, the air outlet is of such size as to offer some resistance to the escape of pressure within the chamber, thus maintaining such pressure as will deter the lcoffee from boiling within the chamber at temperatures around 100 C., or higher, but which is of sufficient size to allow escape of air with sufficient velocity that excessive back-pressure will not be offered to the inlet jet during filling of the chamber, and neither will the coffee be forced out through the filter in any such quantity as to prevent the level within the chamber from rising to the desired height. In the specific apparatus here shown, I form the inner `end of` the air outlet with a conical seat H4, and provide a complementary conical seating surface ||5 on spring end H0, which thus functions asia plug. Seating surface ||5 however, is formed with a roughened or corrugated surface, so that there is a definite air leak provided between the plug and the outlet opening into which it is inserted. The enlarged spring end, or plug, has a similarly corrugated projection ||6 extending inwardly beyond seat H5, such that the plug when engaged within the passage has a secure seat therein and is not apt to become accidentally disengaged. The advantage of the described construction is that the small air outlet as so provided is not apt to become clogged with dirt, as would inevitably occur if the air passage were simply a small hole, of area equivalent to the eil'ectiveair outlet area in my construction. In the construction here shown, ordinary cleaning of the extraction chamber, with the filter and spring removed, will result in maintaining the relatively large passageway in a clean condition, without particular attention being given The filter bag flts snugly over the and the spring end inserted in the air outlet passageway, said passageway is restricted to the proper relatively small eiective cross-sectional area. Thepurpose and effect of this air discharge passage' will appear from the following description oi the operation of the apparatus.

Filter 95 being in place within the extraction chamber, and cover member 20 being removed, groundcoiee in the desired amount is placed in the extraction chamber, and the chamber is then closed. In the specic form of apparatus shown in Fig. 1, this closing of the extraction chamber is done by iirst placing the chamberin position in the top of the boiler, and then mounting top member 2U and pipe fitting 54 in position and engaging clamp device 21 and bail 66. A proper' quantity of water is of course rst placed within boiler 40. The quantity of water required to be placed in the boiler may -be estimated by first iilling the boiler up to the level of outlet 49, and

then adding water approximately equal to theV extraction chamber closes the upper' side of the boiler, and will consequently receive heat from the water being heated within the boiler, and will transmit such heat to the interior of the coiee,

extraction chamber to preheat the ground coffee contained therein while still in a dry' condition.-

As previously mentioned, this dry preheating of the coffee in a closed vessel appears to bring about a release of certain aromatic oils from the ground coiiee, and also to prepare the remainder of the aromatic or volatile essence of the coeev But because no V for rapid assimilation by'water. water is present there is no beginning oi extraction of the non-volatile and water-soluble elements, which include the undesirable parts of the coiee. The extraction chamber being sealed except for the discharge spout, most of the resulting aromatic gases or vapors produced by this preheating operation are confined Within the chamber. The relatively small proportion of the vapor which may pass through the lter and into the outlet passageway, or through the air outlet passageway ii i, are apparently, in practice, preserved by the fact that they condense on the walls of the discharge passageway'and are subsequently taken up by the coee beverage as it is iinally discharged. AIt has been found that not enough of these aromatic vapors pass out into the room to be detected, although if the cover of the chamber be prematurely removed at the end of the preheating stage, avstrong escape of aroma will occur.

It will be evident that the preheating might also be accomplished by separately heating the extraction chamber (with cover 2b in place) before the chamber is placed on the boiler. The

preheating temperature is close to or at 100 C..

and shouldnot be continued for longer than two or three minutes at that temperature, as otherwise the coffee will be given a'bitter taste. This It will be evident that in the form of apparatus shown in Fig. 1, the preheating step described is obtained incidentally by virtue of conduction of heat through extraction chamber bottom Il as the water in boiler 40 rises in temperature. y

As the water within the boiler increases in temperature, the air in the upper part of the boiler expands, and is allowed to escape by way ofgbleeder hole 84; this provision avoids premature build-up of pressure within the boiler and dow of luke warm water outwardly by way of outlet 49 and pipe 50. However, this bleeder hole is not sufdclently large to allow equalization of pressure within and without the boiler after the water within the boiler reaches a boiling temperature, with the result that pressure is nally built up in the upper part of the boiler' forcing out water by way of outlet 49 and pipe 50. The pressure thus produced in the upper portion of the boiler exceeds `atmospheric pressure, and the temperature of the water is accordingly permitted to vrise above boiling temperature at atmospheric pressure. Accordingly, the water rising in pipe 50 is backed up by super-atmospheric pressure, and may be at a temperature above 100 C. Shut-off valve l0 being' open, this water ilows upwardly through pipe 50 and tting 54 and discharges in a at downwardly directedajet from the nozzle member 6l mounted in' theextraction chamber cover. The water thus introduced to the extraction chamber has of course been somewhat cooled during its rise in pipe 50, but is still' near 100 C.

The water so introduced to the extraction chamber then rises up to the level of air vent lll, air previously contained within the cham'- ber escaping through vent ilipast corrugated plug lill and passing outwardly by way of spout I8. The liquid level is prevented from rising further within the chamber by virtue of a "divingbell action df the dome shaped top 20.

The jet of water issuing from orice B2 is so directed as to strike the liquid level surface as thus established approximately in the center, and the jet being under considerable pressure, maintains the entire liquid within the chamber in a state of vigorous agitation. Coffee grounds tending to rise to the surface are repeatedly submerged by this agitating action, and the liquid within the entire chamber is maintained in a state of constant motion, so that no accumulation of coiiee grounds in beds or layers is permitted. Maintenance of the coffee grounds in a state of free suspension in a relatively large quantity o! liquid, and prevention of settling of the grounds on the chamber bottom, or rising to oat as a cake at the top, is a major characteristic of my process and apparatus. `Agitation in the forms shownis accomplished by jet action, but any other method that creates enough agitation will fall within the spirit of the invention, if in combination with the other elements 0f the invention, and producing the same elect. Without this action, Ithe coiee is subject to spoilage due to existence of'relatlvely extreme conditionspf pressure and/or temperature.

The design and adjustment of the apparatus ofA from the boiler, is determined, in the apparatus of Fig. 1, by the adjustment of the boiler blow-oi! valve, which is constituted by the extraction chamber bottom. It will be remembered that adjustment of the spring of the extraction chamber hold-down clamp regulates the steam pressure at which the chamber will lift and vperinit blow-oi of-steam pastsealing washer 4l. This adjustment therefore regulates the temperature of the water sent to theextraction chamber, and

the pressure backing it up. As previously men- I tioned, there is a ,certain coolingof the water in passing through the inlet pipe. If the initial temperature is not too high, this cooling eect willbring the temperature of the water down to a proper usuablelevel at which the beverage does not boil, or suffer ill effects from excessive heat. Higher pressures may be' obviously used by increasing the water cooling surfaces. i

As previously stated, when the herein ldescribed coffee making conditions areestablished, thorough and continuous agitation of the liquid within`the chamber is of utmost necessity, as otherwise spoilage of the coffee is inevitable. The reasons for such spoilage under the conditions of which I speak arexhot entirely obvious, although they may be due to concentration of extracted I' volatile oils and vapors held in the form of a foam of minute bubbles within the bed of coffee grounds,x when such beds are. not constantly broken up. Certain reagents, probably acid, are present in a relatively high concentration in the bubble walls and liquid of the foaming crust and settled bed of grounds. At the temperatures employed, this concentration is sufcient to cause a chemical reaction, resulting in the spoilage before mentioned. If the bed and oating cake of grounds are constantly broken up, and each individual particle of coffee constantly washed 'by an ever-changing bath of water, such concentration of any of the reagents is never permitted, and so no reaction will take place. Whether or not this "theory is fully accountable, it is necessary to emphasize the absolute necessity of thorough agitation, as without it my apparatus would produce a very poor and undrinkable grade of coffee.

fiof

It is of course not essential to my invention, considered in its broader aspects, that the agitation spoken of be accomplished through :letting of the introduced hot water. This form of the invention is simply illustrative of any suitable means capable of thoroughly agitating the liquid within the extraction chamber during the introduction of the hot water and its flow through the chamber.

The form of my invention speciilcally shown in Fig. l incorporates the water discharge nozzle in the removable top or dome of the extraction chamber, so that the introduced water is jettedy downwardly onto the liquid level established by air vent lI/I.- It will be evident that this construction is of particular advantage, in that theliquid-level is prevented from rising to the level of the discharge orice by virtue of a diving-I belli action of the dome, and it is therefore impossible for the liquid level to rise substantiallyl to the level of its discharge outlet 49, and until steam from the boiler has followed up the discharged water and has forced the remainder of Athe coffee through the lter and out the spout.

Thus, in this method of operation, the discharge of the prepared coffee from the apparatus is entirely automatic' in character, the coee extraction chamber first filling with water, and when the liquid level has risen to the height of the air Ent at iii, further introduced water causing coffee to be discharged through the discharge spout, while maintaining the liquid level at the height of the air vent, and* when introduction of water through the coffee chamber ceases, steam from the -boiler following it up and forcing the remaining-coffee to flow from the chamber.

The process is susceptible to several variations. For instance, the quantity of water in the boiler may be just sufficient to fill the extraction chamber up to the level of the air vent, after which steam is at once introduced to the chamber to accomplish the Vautomatic discharge. Thus, in this instance all of the water .is introduced to the chamber before any beverage is drawn off. A similar result of course obtains where any smaller quantity of water is used.

If conditions are such that ow through the apparatusv is too rapid, resulting in incomplete extaneously cut off.

' Attention is particularly called to the. vertically elongated form of lter illustrated in Fig, 1.

' This lter is of especial advantage because of the large filter area which it aords. A filter of small area is found in practice to cause excessive back pressure, with the result that the liquid passing through the water inlet jet does not discharge with sufdciently high velocity to produce the agitation frequired. A filter of the form illustrated, on the other hand, vpermits -the offering of a iilter of sufficient surface without increasing unduly the bottom area of the chamber, and with it the cover size. The vback pressure oiered by the filter (in combination with the air outlet at ill) can then 'be established at that amount which is insufllcient to diminish the energy of the inlet jet below the degree of effectiveness required. The lter should, on the other hand, be

small enough that it will not take up excessive pressures and temperatures independently of one another. In all forms of the apparatus in which the input velocity of the injected hot water is relied upon for agitation of the liquid withinthe extraction chamber, it is essential that an adeouate pressure differential .be maintained between boiler and extraction chamber. This condition can not be established if the water in the extraction chamber retains a temperature at which.

boiling'would occur atthe obtained extraction chamber pressure, it being an essential requirement thatfree boiling ofthe liquid in the chamber be avoided. Furthermore, if the water in the chamber equals the boiler water in temperature,

the vapor thereof will create a back pressure equal to boiler pressure. The desired diierential of pres--Y sure, with a mixing chamber temperature established at the described value, may be secured'by the following illustrative Iorms of apparatus which are in accordance with the present invention.

One such fonn of apparatus is shown in Fig. 8. In that figure, which is .partially diagrammatic, the coiee extraction chamber is indicated atGB,

'and a comparatively high top or dome therefor is shown at |3l, dome |3| in the present instance being of substantially the same size as chamber |30. The increased size of this domey |3l is a feature which may be used as an equivalent for an air vent at pproximately the desired liquid level in cha ber |30 (as used in the form previously described); however, an air vent may be used in the form of Fig, 8 in place of enlarged dome |31 if desired. Chamber 30 is mounted in the upper end of a closed tank i32, which is adapted to be lled with water up to such a level asis indicated. A pipe |33 ex' tends from the lower portion of tank |32 and is coupled to a pipe |3311, projecting through the wall oi' coee extraction chamber i3d, at a level above the water level in tank 32. Pipe i330.

`connects witha downwardly turned tube i331),

terminating in a downwardly directed jet i330 which in this instance is arranged to discharge below the normal liquid level inthe chamber. A pipe |36 communicates with the upper end -of .tank |32, and is provided with a two-way valve |35, which is connected to pipes H35 and |37. Valve i355 is adapted to establish communication between pipes i3d and 536, or between pipes |3d and i3?, as will be apparent from the ligure. Pipe E33 is a steam escape pipe, while pipe i311 is connected to .any sourcev of gas pressure, not indicated.

A cloth covered iilter member lll@ is arranged in extraction chamber i3d, and fits up around the lower end of a coiee draw-o pipe lill which extends downwardly to the lower portion of the extraction chamber. The pipe lill projects outwardly through the side wall of chamber it, and connects to an exterior draw-oliv pipe i152 which may extend to an elevation above the upper end .of the apparatus, if desired, in the manner shown inthe ligure. This draw-oil pipe M2 is shown provided with a stop cock |53, and with a nal discharge spout N4.

Water tank |32 is intended to be maintained at a constant temperature. For this purpose I here indicate an electric heating unit M8, connected to electrical leads |49, in one of which there is a bi-metallic thermostatic control element |53. It will be understood that element 553, -whichs mounted. in proximity to the water in tank 32, so as to be aiected by the heat conducted therefrom, will control the heating of tank |32. The adjustment of the thermostat is such as to maintain the temperature of the water within tank |32 -at the desired operating temperature. Valve |35 is normally in the position shown, so that steam generated in tank 32 escapes through' pipes vi3d and i3d. This prevents any build-up of pressure to a point above boiling in case of failure of the thermostat.

When itis desired to produce coffee, valve 35 is. rotated to position to establish communicashown, the outlet end of pipe |33 is pointed downwardly and is substantially parallel to the wall of the extraction chamber. The direction so given to the injected water maintains the liquid within the extraction chamber in a state of desired agitation. .Airvdisplaced by the water so itroduced is in the speciiic form of apparatus of Fig. 8 caused to .be compressed within the enlarged dome i3l of the apparatus, rather than being allowed to escape through an air vent, as in Fig. l. .When the pressure within chamber |36 hasthus been built up to a certain value, coiee is forced through ilter |413 and caused to vdischarge from the chamber through drawo pipe lill, i132.

This form of apparatus is thus characterized by employment of hot water at a xed, controlled temperature,Y which is independent of the pressure employed to produce the iiow. The pres sure within the water boiler which would be produced by self-generated steam is'below that level required to produce a vigorous action of the water jetwithin the chamber. The water is then forced to now from the water tank into the extraction chamber by employment of a separate source of pressure, which may be as high as desired. The final result is thus to introduce to chamber i3d hot.water at the desired working temperature, backed up by a pressure as high as desired in excess of atmospheric pressure. The conditions are qualitatively the 'same as in the simplepreierred form of Fig. i, but in this form of apparatus there is additional provision for increasing the margin oi pressure between the inlet. source and the chamber without such an accompanying rise of temperature in the introduced water as will cause spoiling of the colee brew.

Fig. 9 shows another variational form of apparatus. In this instance the Vcoiee extraction chamber is indicated at it, and has a closed Atop or dome at iti. The lower end oi chamber m3 is provided with a steam release valve |66,

which may be set to control the boiler pressure at any valve desired. j A water outlet pipe itl leads from boiler i3 from a point |953 near its bottom. This pipe it? has a control valve |63, and above valve its extends inwardly 'and connects to a coil il@ arranged within well 62 and disposed about the lower end of chamber I. The upper end of coil lill connects to a pipe Hi which leads to a water discharge jet i12 discharging within chamber l. As shown; jet H2 is mounted in chamber top lSl.

A small air vent is indicated at l'l, being in this instance placed at a proper point in draworl pipe llt, and establishes the level of liquid within chamber ibi). A cloth covered :filter |15 is shown arranged about the lower end of drawon pipe llt, the latterY leading from the lower portion of chamber it and extending outwardly through the side wall thereof to connect to na discharge spout |18.

This form of apparatus is also typical of apparatus establishing considerable pressure back of the water injected to the extraction chamber, while permitting independent control of the temperature of the injected water. In the operation of this form'of apparatus, the boiler |63 ls heated, and the water therein may rise to a temperature above 100 C., the pressurewithin Y the boiler being allowed to increase to some value above atmospheric pressure before release valve |66 will cpen. The water within well |62 is heated from the boiler, but is prevented from rising above the temperature which it is desired for the inlet water because of release of excess pressure to atmosphere by way of valve |65. Hot water forced from the boiler by the devel-opment of pressure therein and passing upwardly through pipe |51 and coil |10 will be at boiler pressure, but willbe reduced in temperature in passing through the coil |10, which is surrounded by water at the lower temperature which it is desired to establish within the extraction chamber. Consequently, the water injected into the coffee extraction chamber is at boiler pressure but at a temperature somewhatV below boiler temperature.

. These two cases (Figs. 8 and 9) are typical of means which produce such a diierential of pres sure through establishing an'independent control of pressure in the inlet source, on the one hand, and temperature of the inlet water, on the other, giving better control of temperature conditions within the extraction chamber, and at thesame time capability for a greater differential of pressure between thejiot water source and the chamber, with resulting increased jet activity and improved agitation.

It is to be noted that each of the three forms ofapparatus now described have' many individual features of novelty and invention not shown in the other illustrative forms. It will be understood that these various features are contemplated as parts of my invention as a whole, and that many of the features shown on any one of the separate illustrative embodiments may be employed in combination with other features shown on the vother forms, or with other equivalent forms of apparatus not specically illustrated.

It is further to. be vunderstood that while I have now illustrated my invention by describing in detail several specic forms of illustrative apparatus, and by describing my preferred method of making Acoffee with the use of Vsuch apparatus, such typication is for illustrative purposes only, and the invention is to be limited only as may fairly be construed from the following claims.

I claim:

l. In a" coffee making apparatus, the combination of a closed coffee infusion chamber, a

. conduit for conveying hot water to the chamber,

grounds and hot water within the chamber to be' continuously agitated, a filter controlled coffee draw-oil? conduit leading in an `upward direction fromy the lower portion of said chamber, and means for impressing a differential of pressure on the hot water inlet and the coee draw-off conduit such that water flows into the chamber and rises to and slightly above the air vent, followed by ow of liquid from the coiee draw-oi conduit.

2.` In a coffee making apparatus, vthe combination of a closed coffee infusion chamber, a conduit for conveying hot water to the chamber, an air vent near the upper end of the chamber allowing air which has been displaced inthe lower portion of the chamber by the introduced hot water to escape, means causing the coffee grounds and hot -water Within the chamber to be continuously agitated, a filter controlled coiee draw-off conduit leading in an upward direction from the lower portion of said chamber to-a level at least substantially as high as the air vent, and means for introducing hot water to the inlet conduit under sufficient' pressure to flow into and fill the chamber up to and slightly above the air vent and thereafter to ow from the coffee draw-off conduit.

3.l In a coffee making apparatus, the combination of a closed coiee infusion chamber, a conduit for conveying hot water to the chamber, a jet on the discharge end of said conduit for discharging the water within the chamber at a sufcient velocity to vigorously agitate the liquid and coffee grounds in the chamber, an air vent near the upper end of the chamber allowing air which has been displaced in the lower portion of the chamber by the introduced hotwater to escape, and acting to establish the level to which the introduced water may rise within the chamber, a lter controlled coee draw-01T conduit extending upwardly from the lower portion of the chamber to substantially at least the level of the air vent, and means for introducing hot water to the inlet conduit under sumcient pres,- sure to ow into and fdl the chamber up to and slightly above the air vent and to rise in the coee draw-off conduit to substantially the Vlevel of the air vent, and thereafter to iow from the coffee draw-ofi conduit.

4. In a coffee making apparatus, the combination of a closed co-iee infusion chamber, aV conduit for conveying hot water to the chamber, a jet on the discharge end of said conduit for discharging the water within the chamber at a sufficient velocity to vigorously agitate the liquid andcoiee grounds in the chamber, a lter controlled coiee draw-oi conduit extending upwardly from the lower portion of` the chamber,

an air passage leading from a point in the upper end of the chamber into said upwardly extending coffee draw-oi conduit, said air passage allowing air which has been displaced in the lower portion of the chamber by the introduced hot water to escape byV way of the coffee draw-off conduit, and. acting to establish the levelV to which the introduced water may rise within the chamber, and means for introducing hot water to the inlet conduit under suicient pressure to ow into and ll the chamber up to and slightly above the air vent and to rise in the coee drawo conduit to substantially atleast the level of the air vent, and thereafter to flow from the coffee draw-oir conduit.

JOHN STERLING COMSTOCK. 

